package com.lagou.edu.mvcframework.servlet;


import com.lagou.edu.mvcframework.annotations.*;
import com.lagou.edu.mvcframework.pojo.Handler;
import org.apache.commons.lang3.StringUtils;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Parameter;
import java.util.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class LgDispatcherServlet extends HttpServlet {

    private Properties properties = new Properties();

    private List<String> classNames = new ArrayList<>(); // 缓存扫描到的类的全限定类名

    // ioc容器
    private Map<String,Object> ioc = new HashMap<String,Object>();

    private List<Handler> handlerMapping = new ArrayList<>();

    @Override
    public void init(ServletConfig config) throws ServletException {
        String contextConfigLocation = config.getInitParameter("contextConfigLocation");
       //1 加载配置文件
        doLoadConfig(contextConfigLocation);

        // 2 扫描相关的类，扫描注解
        doScan(properties.getProperty("scanPackage"));

        //初始化bean对象(实现ioc容器)
        doInstance();

        // 4 实现依赖注入
        doAutoWired();

        // 5 构造一个HandlerMapping处理器映射器，将配置好的url和Method建立映射关系
        initHandlerMapping();
    }

    private void initHandlerMapping() {
        if (ioc.isEmpty()) return;
        for (Map.Entry<String, Object> entry : ioc.entrySet()) {
            // 获取ioc中当前遍历的对象的class类型
            Class<?> aClass = entry.getValue().getClass();
            if(!aClass.isAnnotationPresent(LagouController.class)){
               continue;
            }
            String baseUrl = "";
            if(aClass.isAnnotationPresent(LagouRequestMapping.class)){
                LagouRequestMapping annotation = aClass.getAnnotation(LagouRequestMapping.class);
                baseUrl = annotation.value(); // 等同于/demo
            }
            //获取方法
            Method[] methods = aClass.getMethods();
            for (int i = 0; i < methods.length; i++) {
                Method method = methods[i];
                if(!method.isAnnotationPresent(LagouRequestMapping.class)) {continue;}
// 如果标识，就处理
                LagouRequestMapping annotation = method.getAnnotation(LagouRequestMapping.class);
                String methodUrl = annotation.value();  // /query
                String url = baseUrl + methodUrl;    // 计算出来的url /demo/query
                // 把method所有信息及url封装为一个Handler
                com.lagou.edu.mvcframework.pojo.Handler handler = new com.lagou.edu.mvcframework.pojo.Handler(entry.getValue(),method, Pattern.compile(url));
                // 计算方法的参数位置信息  // query(HttpServletRequest request, HttpServletResponse response,String name)
                Parameter[] parameters = method.getParameters();
                for (int j = 0; j < parameters.length; j++) {
                    Parameter parameter = parameters[j];
                    if(parameter.getType() == HttpServletRequest.class || parameter.getType() == HttpServletResponse.class){
                        // 如果是request和response对象，那么参数名称写HttpServletRequest和HttpServletResponse
                        handler.getParamIndexMapping().put(parameter.getType().getSimpleName(),j);
                    }else{
                        handler.getParamIndexMapping().put(parameter.getName(),j);  // <name,2>
                    }

                }
                // 建立url和method之间的映射关系（map缓存起来）
                handlerMapping.add(handler);
            }
        }
    }

    private void doAutoWired() {
        if (ioc.isEmpty()) {
            return;
        }
        // 有对象，再进行依赖注入处理
        // 遍历ioc中所有对象，查看对象中的字段，是否有@LagouAutowired注解，如果有需要维护依赖注入关系
        for (Map.Entry<String, Object> entry : ioc.entrySet()) {
            //获取bean字段中的信息
            Field[] declaredFields = entry.getValue().getClass().getDeclaredFields();
            //遍历判断处理
            // 遍历判断处理
            for (int i = 0; i < declaredFields.length; i++) {
                Field declaredField = declaredFields[i];   //  @LagouAutowired  private IDemoService demoService;
                if (!declaredField.isAnnotationPresent(LagouAutowired.class)) {
                    continue;
                }
                LagouAutowired annotation = declaredField.getAnnotation(LagouAutowired.class);
                //获取该bean的id
                String beanName = annotation.value();  // 需要注入的bean的idif
                if ("".equals(beanName.trim())) {
                    // 没有配置具体的bean id，那就需要根据当前字段类型注入（接口注入）  IDemoService
                    beanName = declaredField.getType().getName();
                }

                //开启复制
                declaredField.setAccessible(true);
                try {
                    declaredField.set(entry.getValue(), ioc.get(beanName));
                } catch (IllegalAccessException e) {
                    e.printStackTrace();
                }
            }
        }

    }
    // ioc容器
    // 基于classNames缓存的类的全限定类名，以及反射技术，完成对象创建和管理
    private void doInstance() {
        if(classNames.size()==0)return;
        for(int i = 0;i<classNames.size();i++){
            String className   = classNames.get(i);
            //反射
            try {
                Class<?> aClass = Class.forName(className);
                if(aClass.isAnnotationPresent(LagouController.class)){
                    // controller的id此处不做过多处理，不取value了，就拿类的首字母小写作为id，保存到ioc中
                    String simpleName = aClass.getSimpleName();// DemoController
                    String lowerFirstSimpleName = lowerFirst(simpleName); // demoController
                    Object o = aClass.newInstance();
                    ioc.put(lowerFirstSimpleName,o);
                }else if(aClass.isAnnotationPresent(LagouService.class)){
                    LagouService annotation = aClass.getAnnotation(LagouService.class);
//获取注解value值
                    String beanName = annotation.value();
                    // 如果指定了id，就以指定的为准
                    if(!"".equals(beanName.trim())){
                        ioc.put(beanName,aClass.newInstance());
                    }else{
                        // 如果没有指定，就以类名首字母小写
                        beanName = lowerFirst(aClass.getSimpleName());
                        ioc.put(beanName,aClass.newInstance());
                    }
                    // service层往往是有接口的，面向接口开发，此时再以接口名为id，放入一份对象到ioc中，便于后期根据接口类型注入
                    Class<?>[] interfaces = aClass.getInterfaces();
                    for (int j = 0; j < interfaces.length; j++) {
                        Class<?> anInterface = interfaces[j];
                        // 以接口的全限定类名作为id放入
                        ioc.put(anInterface.getName(),aClass.newInstance());
                    }
                }else{
                    continue;
                }
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            } catch (InstantiationException e) {
                e.printStackTrace();
            }
        }
    }

    private String lowerFirst(String str) {
       char[] chars = str.toCharArray();
       if( 'A'<= chars[0] && chars[0]> 'Z'){
          chars[0] += 32;
        }
       return String.valueOf(chars);
    }

    private void doScan(String scanPackage) {
        String scanPackagePath = Thread.currentThread().getContextClassLoader().getResource("").getPath() + scanPackage.replaceAll("\\.", "/");
        File pack = new File(scanPackagePath);
        File[] files = pack.listFiles();
        for(File file : files){
          if(file.isDirectory()){
              doScan(scanPackage + "." + file.getName());  // com.lagou.demo.controller
          }else if(file.getName().endsWith("class")){
              String className = scanPackage + "." + file.getName().replaceAll(".class", "");
              classNames.add(className);
          }
        }
    }

    private void doLoadConfig(String contextConfigLocation) {
        InputStream resourceAsStream = this.getClass().getClassLoader().getResourceAsStream(contextConfigLocation);
        try {
            properties.load(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req,resp);
    }


    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 处理请求：根据url，找到对应的Method方法，进行调用
        // 获取uri
//        String requestURI = req.getRequestURI();
//        Method method = handlerMapping.get(requestURI);// 获取到一个反射的方法
        // 反射调用，需要传入对象，需要传入参数，此处无法完成调用，没有把对象缓存起来，也没有参数！！！！改造initHandlerMapping();
//        method.invoke() //
        Handler handler = getHandler(req);
        if(handler == null){
            resp.getWriter().write("404 not found");
            return;
        }



        //抽取方法实现方法的拦截
        getresove(handler,req,resp);


        //参数绑定
        // 获取所有参数类型数组，这个数组的长度就是我们最后要传入的args数组的长度
        Class<?>[] parameterTypes = handler.getMethod().getParameterTypes();
        // 根据上述数组长度创建一个新的数组（参数数组，是要传入反射调用的）
        Object[] paraValues = new Object[parameterTypes.length];
        Map<String, String[]> parameterMap = req.getParameterMap();
        // 遍历request中所有参数  （填充除了request，response之外的参数）
        for(Map.Entry<String,String[]> param: parameterMap.entrySet()) {
            // name=1&name=2   name [1,2]
            String value = StringUtils.join(param.getValue(), ",");  // 如同 1,2

            // 如果参数和方法中的参数匹配上了，填充数据
            if(!handler.getParamIndexMapping().containsKey(param.getKey())) {continue;}

            // 方法形参确实有该参数，找到它的索引位置，对应的把参数值放入paraValues
            Integer index = handler.getParamIndexMapping().get(param.getKey());//name在第 2 个位置

            paraValues[index] = value;  // 把前台传递过来的参数值填充到对应的位置去

        }
        int requestIndex = handler.getParamIndexMapping().get(HttpServletRequest.class.getSimpleName()); // 0
        paraValues[requestIndex] = req;


        int responseIndex = handler.getParamIndexMapping().get(HttpServletResponse.class.getSimpleName()); // 1
        paraValues[responseIndex] = resp;

        // 最终调用handler的method属性
        try {
            handler.getMethod().invoke(handler.getController(),paraValues);
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        }

    }

    private void getresove(Handler handler,HttpServletRequest req,HttpServletResponse resp) throws IOException {
        //获得注解以后，从方法中获取值
        String[] users = null;//定义一个数组用来进行传入值的存储
        if(handler.getController().getClass().isAnnotationPresent(LagouSecurity.class)
                ||handler.getMethod().isAnnotationPresent(LagouSecurity.class)){

            if(handler.getController().getClass().isAnnotationPresent(LagouSecurity.class)){
                users = handler.getController().getClass().getAnnotation(LagouSecurity.class).value();
            }
            if(handler.getMethod().isAnnotationPresent(LagouSecurity.class)){
                users = handler.getMethod().getAnnotation(LagouSecurity.class).value();
            }
            System.out.println("当前user的值------------------"+users);
            if((users != null && users.length > 0)){
                String userName = req.getParameter("name");
                boolean flag = Arrays.asList(users).contains(userName);
                System.out.println("前flag的值------------------"+flag);
                if(!flag){
                   req.setCharacterEncoding("UTF-8");
                   resp.setContentType("text/html;charset=utf-8");
                   resp.getWriter().write(userName+"当前用户无权限");
                   return;
                }
            }
        }
    }

    private Handler getHandler(HttpServletRequest req) {
        if(handlerMapping.isEmpty()){return null;}

        String url = req.getRequestURI();

        for(Handler handler: handlerMapping) {
            Matcher matcher = handler.getPattern().matcher(url);
            if(!matcher.matches()){continue;}
            return handler;
        }
        return null;
    }

}
